DIRECT APPROACH
A direct approach usually does not have a wireframing, glazing or underpainting value scale. Can have an underdrawing or none - Abstract Impressionism
One has an underdrawing for guidance while the other one does not.

UNDERDRAWING
• Underdrawings can be done with charcoal, or pastel, acrylic marker or brush as guidelines to work out composition and proportions, and then color is applied
• Color Applications
o Large Spots of Color
o Broken Space Strokes - (Optical Mixing and Simultaneous Contrast )
- Illustrative strokes
- Expressive Strokes
- Final Strokes
DIRECT WITHOUT AN UNDERDRAWING
Is without an underdrawing. Is a direct alla prima painting of large and small spots of color into detailed brushstrokes, usually done for en plein air.

• Color Applications
o Large Spots of Color
o Broken Space Strokes - (Optical Mixing and Simultaneous Contrast )
- Illustrative strokes
- Expressive Strokes
- Final Strokes

In painting your subject you are free to use an many layers or steps to achieve your goal. Studio painting allows for more detailed works, while en plein air needs to work quickly and directly.
There are so many variations to experiment with.